New Alkoxyamines from the Addition of Free Radicals to Nitrones or Nitroso Compounds as Initiators for Living Free Radical Polymerization

Alkoxyamine C–ON Bond Homolysis: Stereoelectronic Effects

“…The upward deviation observed for the faster isomers highlights the enhanced polar effect (Figure 11). For the series 1-22, Figure 12 shows that the (RR/SS) isomers (the slower ones) of 24eR are closer (normal polar effect) to the correlation [Equation (18)] and that the enhanced polar effect is emphasized by the upward deviation of the (RS/SR) isomer of 24eR. Clear evidence and explanations about the polar effect have been given in previous papers.…”

“…Conversely, the faster isomer might display a normal polar effect and the slower one a retarded polar effect (downward deviation). Therefore, the linear regression [Equation (18) and Figure 11] observed for the primary alkoxyamines 24c, 24i, 24k, 24p, 24m and 24u, the nonpolar secondary alkoxyamines 24b and 24o, the tertiary alkoxyamines 24q, 24s, 24dMe and 24g and the secondary polar alkoxyamines 24t and 24w accounts for merely the normal polar effect assuming that the primary and tertiary fragments adopt the same conformation. When 24dtBu and 24dPh are also included in Figure 11, they lie on the straight line [Equation (18)], confirming that the normal polar effect occurs.…”

Synthesis of new open‐chain alkoxyamines and their evaluation for nitroxide‐mediated radical polymerization

“…The tert ‐nitrosobutane is known24 to scavenge C‐centered radicals, affording in situ new nitroxides or even alkoxyamines (Scheme ). Indeed, in situ use of nitroso derivatives for NMP has been reported,25 as has the preparation of the corresponding alkoxyamines and their use for NMP 26. Obviously, the tert ‐nitrosobutane and the new nitroxides formed from it will compete for the propagating radicals with the still‐intact 2.…”

Product Class 5: Hydroxylamines

“…Radical trapping of nitroxides provides an elegant access to O,N,N-trisubstituted hydroxylamines, which by their own serve as initiators or regulators in nitroxide-mediated radical polymerization. [733][734][735][736][737][738] For example, the reaction of bis(trifluoromethyl) nitroxide with toluene produces O-benzyl-N,N-bis(trifluoromethyl)hydroxylamine (527) in 65% yield (Scheme 219). Analogously, benzyl cyanide can be converted into hydroxylamine 528 in 96% yield, and isobutene reacts with bis(trifluoromethyl) nitroxide to give hydroxylamine 529 in 84% yield.…”